It has previously been proposed to use water-hardenable materials in orthopaedic supports and casts; and typical patents disclosing such products include U.S. Pat. No. 4,996,979, granted Mar. 5, 1991, and U.S. Pat. No. 4,683,877, granted Aug. 4, 1987. However, when materials as disclosed in these patents are employed, the flow of liquid through the open cell foam or layers of fabric, as well as the strength of the orthopaedic support may not be subject to the desired level of control.
It is also noted that these prior art products mentioned above have other problems. Thus, for example with regard to the casts or supports using layers of material, care must be taken to firmly engage the layers during the setting period to ensure unitary bonding of the entire layered cast or assembly. Doctors practicing in this area even have a saying: "rub it like you love it," to encourage full engagement of the layers during hardening of the water-hardenable material. This step obviously requires care and expertise, as it is undesirable to apply undue force to an injured limb involving a broken limb, for example. Further, if this technique is not properly employed, the layers will not fully bond together, and the cast or support will be weak, and the layers could separate. Also with regard to the hardenable splints or supports using open cell foam, they may lack sufficient flexibility and conformability to properly fit the three-dimensional parts of the anatomy requiring splinting or support.
Flat rigid panels have also been proposed using double knit fabrics and hardenable resins, as indicated by U.S. Pat. No. 5,166,480, granted Nov. 24, 1992, and entitled "Orthopaedic Sheet-Like Composition." Attention is also directed to U.S. Pat. No. 5,334,442, granted Aug. 2, 1994. This patent discloses an intermediate pliant sheet which may be made of a fabric such as glass fiber impregnated with a water-hardenable material. Then, on both sides of this pliant layer, the patentees disclose the use of layers of double knit material. Thus, with double knit material present in the assembly, it is not used to receive the water-hardenable material but is only used for padding.
As noted above, prior art orthopaedic products have involved shortcomings in the flow control of water to the water-hardenable material and the strength of the orthopaedic device.